1. Cellular Transport

2. Cell Membrane Function:
1. Separate and protect the cell from its surroundings
2. Allow certain substances to pass through it (selectively permeable)

3. Lipid Bilayer Made up of: a. Phospholipids 1. Polar head hydrophilic
2. Non-polar tail
hydrophobic
3. Functions as:
tough, flexible barrier
protects the cell from many substances

4. Lipid Bilayer

5. Lipid Bilayer b. Proteins – some with carbohydrates attached
1. Functions to:
a. form channels and pumps to move material across cell membrane
2. Carbohydrates act as chemical identification cards allowing for recognition of foreign cells by organism

6. Lipid Bilayer

7. Passive Transport animation Passive Transport –
substances move across the cell membrane without using energy
Diffusion:
a. substances move from areas of high
concentration to areas of low concentration
b. can occur with solids, liquids, and gases
c. no energy is used by the cell
animation

9. Diffusion through a membrane
Cell membrane
Outside cell
Inside cell

10. Diffusion through a membrane
Cell membrane
diffusion
Outside cell
Inside cell

11. Diffusion through a membrane
Cell membrane
Outside cell
Inside cell
EQUILIBRIUM

12. Factors Affecting Diffusion Rates
Molecular size
Smaller molecules, faster diffusion
Temperature
Higher temperature, faster diffusion
Electrical or pressure gradients

13. Passive Transport 2. Facilitated Diffusion:
a. substances diffuse across the cell membrane through special protein channels
b. proteins are specific to ions, sugars, salts
c. no energy is used by the cell

14. Passive Transport

15. Facilitated Diffusion through a membrane
Cell membrane
Protein channel
Outside cell
Inside cell

16. Facilitated Diffusion through a membrane
Cell membrane
diffusion
Protein channel
Outside cell
Inside cell

17. Facilitated Diffusion through a membrane
Cell membrane
diffusion
Protein channel
Outside cell
Inside cell
EQUILIBRIUM

18. Facilitated Diffusion: Molecules will randomly move through the opening like pore, by diffusion. This requires no energy, it is a PASSIVE process. Molecules move from an area of high concentration to an area of low conc.

19. Passive Transport
Substances such as alcohol, small lipids, oxygen, water, amino acids & carbon dioxide can dissolve in lipid bilayer therefore can diffuse across the membrane

20. Osmosis
Osmosis:
a. process by which water goes from an area of high concentration (of water) to an area of low concentration (of water) through a selectively permeable membrane
b. deals with water only animation

21. Osmosis CONCENTRATED SOLUTION DILUTE SOLUTION
Cell membrane partially permeable.
Sugar molecule
VERY Low conc. of water molecules. High water potential.
VERY High conc. of water molecules. High water potential.
Outside cell
Inside cell

22. Osmosis Cell membrane partially permeable.
Low conc. of water molecules. High water potential.
OSMOSIS
High conc. of water molecules. High water potential.
Outside cell
Inside cell

23. Osmosis Cell membrane partially permeable. OSMOSIS Outside cell
Inside cell
EQUILIBRIUM. Equal water concentration on each side. Equal water potential has been reached. There is no net movement of water

24. Osmosis c. osmotic (turgor) pressure:
stiffness, rigidity of cells, amount of water present
1. high osmotic pressure
the more water in the cell,
cells become large and inflated (turgid)
2. low osmotic pressure
if water is lost in the cell,
cells become small and deflated
(plasmolysed)

25. Osmosis
Turgid
Plasmolysed

26. Osmosis d. hypertonic solution
the concentration of water inside the cell is greater than outside the cell; therefore the cell will shrink
1. cell will become dehydrated
2. water will leave the cell

27. Osmosis e. hypotonic solution –
the concentration of water outside the cell is greater than inside the cell; therefore the cell will expand
1. cell will become hydrated
2. water will enter the cell

28. Osmosis f. isotonic solution –
the concentration of water outside the cell is equal to the concentration of water inside the cell; therefore the water movement across the cell is equal

29. Osmosis

31. Active Transport B. Active Transport
- energy is needed to move material into or out of the cell
- goes against a gradient
- molecule is too big
animation

32. ACTIVE TRANSPORT Endocytosis:
- process by which organisms bring larger material into the cell
- the membrane actually creates a pocket around the object to bring in
Phagocytosis
- “cellular eating”
- cell membrane surrounds material and creates a food vacuole

34. Active Transport b. Pinnocytosis - “cellular drinking”
- creates a water vacuole
2. Exocytosis:
- process by which organisms use energy to get rid of materials that it doesn’t need

35. Active Transport